Current methods for treating or processing animal substrates such as skins, hides, pelts, and leather necessitate the use of vast quantities of water. For example, in treatment methods wherein the animal substrate comprises a hide, typically 30 kg of water is required per kg of hide. Large volumes of water are needed in order to remove unwanted materials from the animal substrate (such as those that are liable to decomposition) and in subsequent steps of the process which involve chemical modification to confer certain properties on the animal substrate. Chemical modification of the substrate may be carried out for the purpose of, inter alia, preserving, waterproofing, colouring and/or providing any desired textural or aesthetic qualities. The various steps described above will generally be performed in the presence of a treatment formulation comprising one or more components. Large volumes of water can also be required in conventional steps or processes of adding a colourant to such an animal substrate.
Due to the large quantity of water relative to the weight of animal substrate, current treatment processes known in the art require a commensurate increase in the amount of chemicals used in the treatment formulation to ensure an effective treatment of the substrate within an acceptable timeframe. Consequently, excessive amounts of polluting and environmentally damaging effluents can be produced from such processes. Furthermore, because only low levels of mechanical action can be used to avoid damaging the animal substrate, long process times can be necessary.
Many of the methods for preparing animal substrates for human use still remain predominantly based on traditional processes and there have been few advances in recent years. For example, methods for the processing and manufacturing of leather have remained largely unchanged for 75 years. EP0439108 filed in 1991 and directed to a process using carbon dioxide for deliming of hides, discloses an example of one of the few recent developments in this field.
Prior to the development of the method disclosed herein, the inventors have previously addressed the problem of reducing water consumption in a domestic or industrial cleaning method. Thus, in WO-A-2007/128962 there is disclosed a method and formulation for cleaning a soiled substrate, the method comprising the treatment of the moistened substrate with a formulation comprising a multiplicity of polymeric particles, wherein the formulation is free of organic solvents. However, although the process disclosed therein relates to an improved means for cleaning a soiled substrate requiring less water, the application does not disclose a method or process for treating an animal substrate.
There is therefore needed an improved method for treating or preparing an animal substrate which ameliorates or overcomes the above-noted problems associated with the methods of the prior art. In particular there is a need for an improved method of treating an animal substrate by adding a colourant to an animal substrate. Particularly, there is needed a method for treating an animal substrate which can require less water than the methods of the prior art and that can reduce the volume of polluting and hazardous effluent produced from such a method. Furthermore, there is a desired a method for treating an animal substrate which can be advantageous in being faster, more efficient and in providing a substrate with improved properties when compared with methods of the prior art. Still further there is desired for a method of treating an animal substrate which can provides a substrate which can have one or more of the following properties:    i. Deeper penetration of the treatment formulation into the animal substrate;    ii. More uniform treatment of the surface of the animal substrate;    iii. Improved fixation of the treatment formulation components into the animal substrate;    iv. Improved surface aesthetics including feel and appearance; and    v. Improved longevity of the final treated substrate.